linux-kernel - [PATCH v5 2/9] x86/head: Move the early NMI fixup into C

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Message-Id: <dd068269f8d59fe44e9e43a50d0efd67da65c2b5.1459605520.git.luto@kernel.org>
Date:	Sat,  2 Apr 2016 07:01:33 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	X86 ML <x86@...nel.org>
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	KVM list <kvm@...r.kernel.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	xen-devel <Xen-devel@...ts.xen.org>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v5 2/9] x86/head: Move the early NMI fixup into C

C is nicer than asm.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/kernel/head_32.S | 7 -------
 arch/x86/kernel/head_64.S | 6 ------
 arch/x86/mm/extable.c     | 5 +++++
 3 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index bef3e6c49b56..5e6ce845813a 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -555,9 +555,6 @@ early_idt_handler_common:
 	 */
 	cld
 
-	cmpl $2,(%esp)		# X86_TRAP_NMI
-	je .Lis_nmi		# Ignore NMI
-
 	cmpl $2,%ss:early_recursion_flag
 	je hlt_loop
 	incl %ss:early_recursion_flag
@@ -636,10 +633,6 @@ early_idt_handler_common:
 hlt_loop:
 	hlt
 	jmp hlt_loop
-
-.Lis_nmi:
-	addl $8,%esp		/* drop vector number and error code */
-	iret
 ENDPROC(early_idt_handler_common)
 
 /* This is the default interrupt "handler" :-) */
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index f8d6dad41e8d..af87896b6a23 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -354,9 +354,6 @@ early_idt_handler_common:
 	 */
 	cld
 
-	cmpl $2,(%rsp)		# X86_TRAP_NMI
-	je .Lis_nmi		# Ignore NMI
-
 	cmpl $2,early_recursion_flag(%rip)
 	jz  1f
 	incl early_recursion_flag(%rip)
@@ -425,9 +422,6 @@ early_idt_handler_common:
 20:	/* Exception table entry found or page table generated */
 	decl early_recursion_flag(%rip)
 	jmp restore_regs_and_iret
-.Lis_nmi:
-	addq $16,%rsp		# drop vector number and error code
-	INTERRUPT_RETURN
 ENDPROC(early_idt_handler_common)
 
 	__INITDATA
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 176e48de25d4..d6e4e6fb4002 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -2,6 +2,7 @@
 #include <linux/spinlock.h>
 #include <linux/sort.h>
 #include <asm/uaccess.h>
+#include <asm/traps.h>
 
 typedef bool (*ex_handler_t)(const struct exception_table_entry *,
 			    struct pt_regs *, int);
@@ -96,6 +97,10 @@ int __init early_fixup_exception(struct pt_regs *regs, int trapnr)
 	unsigned long new_ip;
 	ex_handler_t handler;
 
+	/* Ignore early NMIs. */
+	if (trapnr == X86_TRAP_NMI)
+		return 1;
+
 	e = search_exception_tables(regs->ip);
 	if (!e)
 		return 0;
-- 
2.5.5